The present invention relates to Wireless Local Area Network (WLAN) Radio networks interworking with a 3GPP (3rd Generation Partnership Project) System. 3GPP-WLAN Interworking is used generically to refer to interworking between the 3GPP system and the WLAN family of standards. A WLAN that interworks with a 3GPP system is denoted Interworking WLAN (I-WLAN).
FIG. 1 illustrates an I-WLAN system architecture according to the prior art standard. WLAN 3GPP IP Access 25 allows WLAN User Equipments (UEs) 5 to establish connectivity with other IP networks, such as 3 G operator networks, corporate Intranets or the Internet via the 3GPP system. A WLAN Access Network 10 includes WLAN Access Points (AP). The system architecture involves an intermediate AAA (Authentication, Authorisation and Accounting) elements 40, and may additionally include other devices such as routers. The WLAN UE 5 includes all equipment that is in possession of the end user, such as a computer, WLAN radio interface adapter etc.
When an UE 5 is to access a IP Network 15, or a Private Network, this access may be provided via the WLAN 3GPP IP Access. The UE 5 sends its packet in an IP protocol that has to be tunneled through WLAN Access Network (AN) 10 and the 3GPP IP Access Network 25. Tunneling means that the IP packets that are transported in an Internet Protocol are transported in another protocol that is addressed with a local IP address.
A WLAN Access Gateway (WAG) 35 in the IP Access network 25 will route the data packet traffic through the WLAN 3GPP IP Access network. The function of said network element is described in reference 2, e.g. chapters 6.2.5.
When using WLAN Direct IP Access 12 directly to internet 15, a WLAN UE 5 needs to use its local IP (LIP) address only. In the other case, when using WLAN 3GPP IP Access 25, a WLAN UE 5 has to shall use two IP addresses: its local IP (LIP) address and a remote IP (RIP) address. For the WLAN assigned LIP address, which belongs to the address space of WLAN AN, there is no additional requirement on the WLAN. When using WLAN 3GPP IP Access, a WLAN UE's RIP address identifies the WLAN UE in the network that the WLAN UE is accessing for the 3G PS (Packet Switched) service. It shall be used for the inner packet of the WLAN UE-initiated tunnel. It can be assigned by the Home Public Land Mobile Network (HPLMN), Visited PLMN (VPLMN) or another IP network. The RIP address can be statically or dynamically assigned. The only case where VPLMN assigns the RIP address for the WLAN UE is when the WLAN UE-initiated tunnel terminates at the VPLMN's Packet Data Gateway (PDG). When the WLAN UE's RIP address is allocated by a second IP network, the PDG is required to have an interface with an address allocation server, such as AAA or Dynamic Host Configuration Protocol (DHCP), belonging to the IP network. For the WLAN UE's RIP address, IPv4 addresses shall be supported. When the WLAN UE accesses 3G PS based services using an IPv6 network such as IMS services, IPv6 addresses shall be supported for the WLAN UE's RIP address. When a WLAN UE accesses several 3G PS based services with different W-APNs simultaneously, the WLAN UE can get several RIP addresses. There may be several WLAN UE-initiated tunnels for the services.
The determination of the location of an attached User Equipment in a tunneled IP network such as an I-WLAN is not yet possible, even though TISPAN has specified procedures for position determination of an IMS user based on the remote (PDP) IP address also when the 3GPP IP access as specified is used. The problem is that there is no binding/associating of the local IP address and its associated geographical information to the WLAN UE remote IP address in the case of a WLAN UE that is attached via an I-WLAN to a another, second IP network or Internet.